Use of Heat Stress Responsive Gene Expression Levels for Early Selection of Heat Tolerant Cabbage (Brassica oleracea L.)

Abstract

Cabbage is a relatively robust vegetable at low temperatures. However, at high temperatures, cabbage has disadvantages, such as reduced disease tolerance and lower yields. Thus, selection of heat-tolerant cabbage is an important goal in cabbage breeding. Easier or faster selection of superior varieties of cabbage, which are tolerant to heat and disease and have improved taste and quality, can be achieved with molecular and biological methods. We compared heat-responsive gene expression between a heat-tolerant cabbage line (HTCL), “HO”, and a heat-sensitive cabbage line (HSCL), “JK”, by Genechip assay. Expression levels of specific heat stress-related genes were increased in response to high-temperature stress, according to Genechip assays. We performed quantitative RT-PCR (qRT-PCR) to compare expression levels of these heat stress-related genes in four HTCLs and four HSCLs. Transcript levels for heat shock protein BoHsp70 and transcription factor BoGRAS (SCL13) were more strongly expressed only in all HTCLs compared to all HSCLs, showing much lower level expressions at the young plant stage under heat stress (HS). Thus, we suggest that expression levels of these genes may be early selection markers for HTCLs in cabbage breeding. In addition, several genes that are involved in the secondary metabolite pathway were differentially regulated in HTCL and HSCL exposed to heat stress.

Overexpression of a Brassica campestris HSP70 in tobacco confers enhanced tolerance to heat stress

“…Cabbage is a kind of important and favorite vegetable in Asia countries such as China, Korea, etc., which is relatively robust at low temperatures than high temperatures, whereas high temperatures always caused serious quality decrease and reduced yields (Park et al 2013). Therefore, it is important to culture new heat-tolerant cabbage varieties.…”

Analysis of Brassica oleracea early stage abiotic stress responses reveals tolerance in multiple crop types and for multiple sources of stress

“…Genechip assays have been used to compare expression patterns to differentiate between heat‐tolerant and heat‐susceptible cabbage lines, showing that heat‐tolerant lines show increased expression of heat shock proteins . Differential protein expression has also been noted in heat‐tolerant and heat‐sensitive cauliflower lines .…”

“…Temperature during the growth period has been shown to impact upon the growth of B. oleracea crops. For example, cabbage plants have been found to show reduced disease tolerance and lower yields at high temperatures . Both low and high temperatures have been reported to affect stomatal conductance and fresh weight in cabbage and kale, but with kale appearing more susceptible to changes in air temperature than cabbage …”

Association mapping of agronomic traits of canola (Brassica napus L.) subject to heat stress under field conditions

“…This gene is involved in tapetal development, programmed cell death (PCD) and pollen grain sterility (Zhang et al, 2014). Many other genes such as 2-oxoglutarate (2OG) and Fe(II)-dependent oxygenase superfamily protein (Leisner et al, 2014), cysteine/histidine-rich C1 domain family protein (Zhang et al, 2014), heat shock protein 18.2 (Kim and Hong, 2001), zinc finger (C3HC4-type RING finger) family protein (Wu et al, 2014), cellulose synthase like A14 (Park et al, 2013), homeodomain-like superfamily protein (Wilson et al, 2011), syntaxin of plants 71 (Sharma and Nayyar, 2014), cellulose synthase 5 (Park et al, 2013), plant selfincompatibility protein S1 family (Samuel et al, 2009), cytochrome P450 (Zhao et al, 2015), ubiquitin family protein (Mazzucotelli et al, 2006), malectin/receptor-like protein kinase family protein (Matschi et al, 2013), glutamine synthetase 1;4 (Bargaz et al, 2015), auxin response factor 19 (Li et al, 2016), AGAMOUS-like 24 (Yu et al, 2002), P450 reductase 1 (Bak et al, 2011) were also identified associated with the cytoplasmic male sterility, pollen tube and pollen coat development, boron deficiency, and seed pod development.…”