Young kiwifruit seedlings(Actinidia deliciosa and A. chinensis)were planted in nutrient solutions aerated with nitrogen. Under root-zone hypoxia stress, the growth and response of endogenous hormones abscisic acid (ABA), indole-acetic acid (IAA), zeatin riboside (ZR), gibberellins (GA3) in kiwifruit seedlings were studied. The results showed that the fresh and dry weight of seedlings treated under hypoxia were less than those of control. Effects of hypoxia stress on A. deliciosa were much slighter than on A. chinensis, which made A. deliciosa perform a better resistance. The ABA contents in A. deliciosa, A. chinensis leaves and roots were enhanced obviously, namely raised by 289.2%, 412.9%, 188.5%, 177.4%, respectively. The IAA contents in A. deliciosa, A. chinensis leaves were raised to the maximum on the 6th day, then reduced but still higher than those of control, namely raised by 87.3%, 61.4%, respectively. Same tendencies happened in the roots of both species, but the peak appeared on the 4th day and differed from that for the leaves. The IAA contents in roots of A. deliciosa, A. chinensis were increased by 90.4%, 59.6%, respectively. The GA3 and ZR contents in A. deliciosa, A. chinensis leaves were decreased by 56.5%, 79.0%, 70.5%, 86.1% correspondingly. The GA3 and ZR contents in A. deliciosa, A. chinensis in roots were lessened by 33.1%, 55.1%, 46.9%, 71.3% correspondingly. The ratios of IAA/ABA, ZR/ABA, GA3/ABA were also studied and the results of them decreased, which showed that kiwifruit seedlings were obviously inhibited from growing under hypoxia and the resistant ability had an intimate relationship with endogenous hormones.
Four genotypes of capsicum (Capsicum annuum L.) with distinct low light tolerance were used to study the response of anatomical structure, ultrastructure of chloroplast,stomatal characteristics and photosynthetic characteristics of leaves to low light (75~100 μmol·m-2·s-1) in a phytotron. The results revealed that leaves treated with low-light became thinner with an increase of palisade/spongy tissue ratio, and two genotypes including hot pepper ‘Fudijian’and sweet pepper ‘Shanghai Yuanjiao’had higher ratio than the other two. Under low light, the number of chloroplast decreased, but the size of chloroplasts and starch grains, the number of grana, grana lamella, starch grain and grana thickness of chloroplast increased. Comparing with sweet pepper, hot pepper had more chloroplasts and granas. In sweet pepper, the stomatal density in lower epidermal descended during leaf unfolding, but no more changes of stomatal index and number of stomata per leaf occurred after 14 day of leaf unfolding. Low light treatment resulted in decreases of stomatal density, stomatal index and number of stomata per leaf, and increases of the stomatal size, the vertical and horizontal axes of stomata in ‘Shanghai Yuanjiao’. Simultaneously, the longer horizontal axes of stomata were also observed in another genotype ‘20078’. The epidermal cells of sweet pepper grown under low light were large and distorted. Meanwhile the stomata and lower epidermal cell were equal height or the stomata slightly protruded out of the epidermal wall. The cycle wrinkle could be obviously observed on cuticle of guard cell in lower epidermis of leaves under low light. Photosynthetic parameters including light saturated rate of the CO2 assimilation (Asat), dark respiration rate (Rd), night respiration rate (Rn), light respiration rate (Rp), light compensation point (LCP), light saturation point (LSP), CO2 compensation point (Г), CO2 saturation point (CSP), carboxylation efficiency (CE) and maximum RuBP regeneration rate decreased, while apparent quantum yield (Фi) increased under low light. The Asat decreasing, LCP, LSP, Rd, Rn and Rp were lower in hot pepper than those in sweet pepper. The start time of photosynthesis (namely, the net photosynthetic rate i.e. Pn from zero to maximum) in low-light leaves was relatively prolonged, especially in low light-sensitive than in low light-tolerant genotypes. Hence, some adaptive response of photosynthetic characteristic to low light have happened in capsicum leaves.
To make clear the intrinsic mechanism of cold resistance of grafted cucumber,changes of relative expression and activities of antioxidant enzymes in the AsA-GSH circle and the contents of AsA, GSH and H202 were tested in the leaves of either own-root cucumber (Junlv No. 3) or grafted plants where cucumber (Junlv No. 3) was grafted on black-seed pumpkin. Both plants were treated under low-temperature stress. The results showed that, under low-temperature stress, the relative expressions of DHAR, and GR mRNA were all higher in the leaves of grafted cucumber than that of own-root cucumber, while no significant changes were found in the relative expressions of GalLDH and APX mRNA; the contents of AsA, GSH and the ratio of AsA/DHA, GSH/GSSG were all higher in grafted cucumber than that of own-root cucumber, while the contents of DHA, GSSG and H2O2 were all lower. We concluded that the higher activities of DHAR and GR, which were from the higher relative expression of DHAR and GR mRNA, were mainly responsible for the higher contents of ASA and GSH in the grafted cucumber leaves. But the higher activities of GalLDH and APX have nothing to do with the relative expression of GalLDH and APX.
Isolated microspore culture in cucumber was studied by using 10 different varieties of cucumber. Cotyledonary embryoids and plantlets were obtained from '7447' and 'Poinsett97' genotypes for the first time. The results showed that genotype and the developmental stage of microspore were the key factors in embryoid induction. The embryoid yield was different significantly among different genotypes. Embryoid yield per culture dish varied from 1.5~33.4. The late-uninucleate stage of microspore was found optimum for isolated microspore culture in cucumber. Cold-pretreatment (4 ℃) for 2~4 days also promoted embryoid induction, while the highest embryoid yield was obtained form microspore pre-treated at 4 ℃ for 2 days. The results also indicated that low concentration of exogenous hormones (0.5 mg·L-1 2,4-D and 0.2 mg·L-1 6-BA) were conductive to embryogenesis, whereas NLN and B5 medium had no significant difference on embryoid induction. The regenerated plantlets were obtained only from cotyledonary embryoids and no plantlet was produced from the embryoids at other developmental stages.
Tree peony cut flower (Paeonia suffruticosa 'Luo Yang Hong') harvested in the first grade of flower opening index was taken as material to investigate the influence of exogenous ethylene and ethylene action inhibitor 1-MCP on flower opening index, diameter increasing rate, vase life, endogenous ethylene production and ethylene biosynthetic enzymes activities of ACC synthase (ACS) and ACC oxidase (ACO) during postharvest opening and senescence. The results showed that 10 μL·L-1 ethylene treatment for 6 h hastened the process of flower opening, shortened vase life and induced petals abscission seriously after full-open; while 1.0 μL·L-1 1-MCP retarded flower opening, prolonged flower vase life and impeded full-open of some flowers. Endogenous ethylene production was promoted by ethylene and inhibited by 1-MCP respectively, which was closely associated with the flower opening process. ACS and ACO activities analysis after different treatments indicated that changes in ACS activity were related to the endogenous ethylene production, suggesting that ACS is the main factor in the regulation of tree peony cut flower opening and senescence, which confirmed the former conclusion that ACS is the rate-limiting enzyme in plants ethylene biosynthesis.
The expression pattern of NTMADS1 gene, a flower organ identity gene from Narcissus tazetta var. chinensis, was analyzed by RT-PCR. The results revealed that the transcript of NTMADS1 was not detectable in vegetative tissues, but only in flowers. Within open flower organs, transcript levels were much higher in stamen and corana than in pistil and barely detectable in petals. NTMADS1 gene was subcloned into the multiple cloning sites of pBI121 vector drived by 35S promoter, and was transferred into Arabidopsis thaliana by Agrobacterium tumefaciens. Ectopic expression of NTMADS1 in transgenic A. thaliana plants resulted curly leaves, early flowering and shape-changed flowers.
A fast chlorophyll fluorescence parameters were measured in two varieties of eggplants, Duanbahei with colder tolerance and Heishuai with higher temperature tolerance by Plant Efficiency Analyzer (PEA). Also the thermodynamics analyse of PSⅡ cold shock stability were studied by using the standard stade denaturalization Gibbs free energy variation △GD of the maximal photochemical efficiency of photosystem Ⅱ (Fv/Fm) and reaction centers RC/CSo . With the temperature decreasedand time extended, The Fv/Fm of PSII, factual photochemistry efficiency ΔF/Fm′ and RC/CSo were "S" downtrend.The exhibition of the energy dissipation DIo/RC and the nonphotochemical quenching coefficient qN were "S" ascends.The generalized analysis reflected the dual mechanism under the cold shock, the reversible deactivation of PSⅡ reaction centers and the energy dissipation which depended on lutein circulation were important in protecting PSⅡ for preventing photoprohibition. Moreover, two groups of new parameters were introduced as index for comparing cold shock easily through the different PSⅡ action of two varieties. Semi-attenuation temperature T1/2 and t1/2 of Heishuai were 1.4 ℃ and 0.8 ℃ higher than that of Duanbahei. The △GD of the Fv/Fm and RC/CSo in the leaves of eggplant were "waterfall" downtrend with the cold shock temperature decreased.The △GD and the denaturalization midpoint temperature Tm of Heibei were lower than Duanbahei. The result showed the cold tolerance of Heishuai is lower than Duanbahei.
Anther anatomical structure and development was observed using a light microscope through paraffin slices on the mustard tubers cytoplasmic male sterility line(CMS) and its corresponding maintainer line in tetraploid Chinese cabbage. The results showed that this allogenic cytoplasmic male sterility belongs to structural male sterility. There were five types in the degraded and abnormal stamens as follows:(1)peltate stamen;(2)stripe stamen;(3)sheet stamen;(4)pinnate stamen;(5)petaloid stamens. The anther development of the tetraploid chinese cabbage CMS was inhibited at two stage. The abortion of peltate stamen anther occurred at the stage of archesporial cell differentiation, at which there was no differentiation of fibrous layer, middle layers, tapetum and microspore mother cell and no anther sac formed. Peltate stamen of the allogenic cytoplasmic male sterility line belongs to non-sporange cytoplasmic male sterility. And the abortion of other types anther might occur at the stage of stamen anlage polarization. The stamen anlage deviated from the normal polarization and formed petal anlage, developing into petal.
Through RT-PCR technique 1 324 bp cDNA sequence of S locus glycoprotein gene (BcSLG) was obtained from self-incompatible line with specific primers in Brassica campestris ssp.chinensis. Sequence analysis indicated BcSLG contained one open reading frame, which encoded 432 amino acids with 12 conserved cysteine residues and 7 potential N-linked glycosylation sites. Sequence alignment and phyologenetic analysis revealed BcSLG had high similarity to SLG from other plants and had closest phylogenetic relationship to that in Brassica campestris L. and Brassica oleracea L. Real-time PCR analysis showed BcSLG was highly expressed in stigmas, much lower in buds and lowest in leaves of self-incompatible line. However, in self-compatible line BcSLG was expressed in an even lower level whether in stigmas, buds or leaves.
Cytoplasmic male sterility (CMS) is one of the most important materials to produce hybrid seeds of many crops. Advances of breeding and studies in onion (Allium cepa L.) cytoplasmic male sterility are described in this paper, and the mechanisms and molecular markers of cytoplasmic male sterility in onion are summarized. A few proposals on breeding and studies in onion cytoplasmic male sterility are put forward on the bases of reviews mentioned above.