Natural variation in glycine-rich region of Brassica oleracea cold shock domain protein 5 (BoCSDP5) is associated with low temperature tolerance.

BACKGROUND: Low temperature (LT) or cold stress is a major environmental stress that seriously affects plant growth and development, limiting crop productivity. Cold shock domain proteins (CSDPs), which are present in most living organism, are involved in RNA metabolisms influencing abiotic stress tolerance. OBJECTIVE: The aims of this study are to identify target gene for LT-tolerance, like CSDPs, characterize genetics, and develop molecular marker distinguishing LT-tolerance in cabbage (Brassica oleracea var. capitata). METHODS: Semi-quantitative RT-PCR or qRT-PCR was used in gene expression study. LT-tolerance was determined by electrolyte leakage and PCR with allelic specific primers. RESULTS: Allelic variation was found in BoCSDP5 coding sequence (CDs) between LT-tolerant (BN106 and BN553) and -susceptible inbred lines (BN107 and BN554). LT-tolerant inbred lines contained variant type of BoCSDP5 (named as BoCSDP5v) which encodes extra CCHC zinc finger domain at C-terminus. Association of LT-tolerance with BoCSDP5v was confirmed by electrolyte leakage and segregation using genetic population derived from BN553 and BN554 cross. Allelic variation in BoCSDP5 gene does not influence the rate of gene expression, but produces different proteins with different number of CCHC zinc finger domains. LT-tolerance marker designed on the basis of polymorphism between BoCSDP5 and BoCSDP5v was confirmed with samples used in previous B. oleracea CIRCADIAN CLOCK ASSOCIATED 1 (BoCCA1) marker validation. CONCLUSIONS: LT-tolerant allele (BoCSDP5v) is dominant and independent of CBF pathway, and sufficient to generate molecular markers to identify LT-tolerant cabbage when it is used in combination with another marker, like BoCCA1-derived one. Production and analysis of overexpressing plants of BoCSDP1, BoCSDP3, BoCSDP5 and BoCSDP5v will be required for elucidating the function of CCHC zinc finger domains in LT-tolerance.

Exogenous Methyl Jasmonate and Salicylic Acid Induce Subspecies-Specific Patterns of Glucosinolate Accumulation and Gene Expression in Brassica oleracea L.

Glucosinolates have anti-carcinogenic properties. In the recent decades, the genetics of glucosinolate biosynthesis has been widely studied, however, the expression of specific genes involved in glucosinolate biosynthesis under exogenous phytohormone treatment has not been explored at the subspecies level in Brassica oleracea. Such data are vital for strategies aimed at selective exploitation of glucosinolate profiles. This study quantified the expression of 38 glucosinolate biosynthesis-related genes in three B. oleracea subspecies, namely cabbage, broccoli and kale, and catalogued associations between gene expression and increased contents of individual glucosinolates under methyl jasmonate (MeJA) and salicylic acid (SA) treatments. Glucosinolate accumulation and gene expression in response to phytohormone elicitation was subspecies specific. For instance, cabbage leaves showed enhanced accumulation of the aliphatic glucoiberin, progoitrin, sinigrin and indolic neoglucobrassicin under both MeJA and SA treatment. MeJA treatment induced strikingly higher accumulation of glucobrassicin (GBS) in cabbage and kale and of neoglucobrassicin (NGBS) in broccoli compared to controls. Notably higher expression of ST5a (Bol026200), CYP81F1 (Bol028913, Bol028914) and CYP81F4 genes was associated with significantly higher GBS accumulation under MeJA treatment compared to controls in all three subspecies. CYP81F4 genes, trans-activated by MYB34 genes, were expressed at remarkably high levels in all three subspecies under MeJA treatment, which also induced in higher indolic NGBS accumulation in all three subspecies. Remarkably higher expression of MYB28 (Bol036286), ST5b, ST5c, AOP2, FMOGS-OX5 (Bol031350) and GSL-OH (Bol033373) was associated with much higher contents of aliphatic glucosinolates in kale leaves compared to the other two subspecies. The genes expressed highly could be utilized in strategies to selectively increase glucosinolate compounds in B. oleracea subspecies. These results promote efforts to develop genotypes of B. oleracea and other species with enhanced levels of desired glucosinolates.

AtGSNOR1 function is required for multiple developmental programs in Arabidopsis.

Nitric oxide (NO) has been proposed to regulate a diverse array of activities during plant growth, development and immune function. S-nitrosylation, the addition of an NO moiety to a reactive cysteine thiol, to form an S-nitrosothiol (SNO), is emerging as a prototypic redox-based post-translational modification. An ARABIDOPSIS THALIANA S-NITROSOGLUTATHIONE (GSNO) REDUCTASE (AtGSNOR1) is thought to be the major regulator of total cellular SNO levels in this plant species. Here, we report on the impact of loss- and gain-of-function mutations in AtGSNOR1 upon plant growth and development. Loss of AtGSNOR1 function in atgsnor1-3 plants increased the number of initiated higher order axillary shoots that remain active, resulting in a loss of apical dominance relative to wild type. In addition atgsnor1-3 affected leaf shape, germination, 2,4-D sensitivity and reduced hypocotyl elongation in both light and dark grown seedlings. Silique size and seed production were also decreased in atgsnor1-3 plants and the latter was reduced in atgsnor1-1 plants, which overexpress AtGSNOR1. Overexpression of AtGSNOR1 slightly delayed flowering time in both long and short days, whereas atgsnor1-3 showed early flowering compared to wild type. In the atgsnor1-3 line, FLOWERING LOCUS C (FLC) expression was reduced, whereas transcription of CONSTANS (CO) was enhanced. Therefore, AtGSNOR1 may negatively regulate the autonomous and photoperiod flowering time pathways. Both overexpression and loss of AtGSNOR1 function also reduced primary root growth, while root hair development was increased in atgsnor1-1 and reduced in atgsnor1-3 plants. Collectively, our findings imply that AtGSNOR1 controls multiple genetic networks integral to plant growth and development.