Impact of grafting on cold responsive gene expression in Satsuma mandarin (Citrus unshiu)

Abstract

The major limitation preventing the expansion of Satsuma mandarin (Citrus unshiu) production in the Gulf Coast regions of the US is the risk of freeze damage. Poncirus trifoliata (L.) Raf has been widely used as a cold hardy rootstock for citrus production in freeze-prone environments. In this study, relative quantitative real-time RT-PCR was used to study cold responsive genes in Satsuma mandarin (C. unshiu), C. unshiu grafted on P. trifoliata rootstock and P. trifoliata following exposure to cold shock or cold acclimation treatments. Major changes in gene expression occurred in the different species during cold stress especially with respect to nitrate transporter, auxin responsive GH3, UDP-glycosyltransferase (UGT) and chalcone-flavanone isomerase. Very high levels of nitrate transporter were reached early in Poncirus following 60 h of cold shock treatment at 4°C, and in C. unshiu after 3 weeks of gradual cold acclimation. Also, high levels of auxin responsive GH3 were reached in Poncirus following both cold shock and cold acclimation, while levels in C. unshiu were low or reduced. Poncirus rootstock significantly affected gene expression in C. unshiu scion, resulting in a reduction of nitrate transporter, UGT and trehalose 6-phosphate synthase expression levels, and an increase in auxin responsive GH3 gene during cold acclimation. The impact of rootstock on citrus scion during cold stress might be associated with partitioning of nutrients and hormones.

Genome Wide Transcriptional Profile Analysis of Vitis amurensis and Vitis vinifera in Response to Cold Stress

“…Very high transcript levels of nitrate transporter (431 fold increase) were observed in Poncirus , a cold hardy rootstock for citrus. While much lower levels were observed in Satsuma mandarin [62]. Higher transcription level of nitrate transporter gene indicates the possible role in nitrate acquisition in cold-hardness V. amurensis .…”

“…The expression of a nitrate transporter gene NRT2 (At1g08090) was induced by cold, mannitol and NaCl treatment in the root of Arabidopsis [61]. Species specific expression differences of nitrate transporter were observed in citrus upon exposure to 4°C [62]. Very high transcript levels of nitrate transporter (431 fold increase) were observed in Poncirus , a cold hardy rootstock for citrus.…”

Ectopic expression of citrus UDP-GLUCOSYL TRANSFERASE gene enhances anthocyanin and proanthocyanidins contents and confers high light tolerance in Arabidopsis

“…Duncan) and positively correlated with flavonoids biosynthesis [35]. The UGT708G1 from kumquat (Fortunella crassifolia) and UGT708G2 from satsuma mandarin (Citrus unshiu) are involved in flavonoids accumulation [36] and regulates the anthocyanin pigments biosynthesis [37] and in citrus UGTs genes respond to different environmental conditions [51,52]. To the author's knowledge, this study provided an evidence of UGT78D3s' function in both anthocyanins and proanthocyanidins.…”

Screening Differential Expressions of Defense-related Responses in Cold-treated 'Kyoho' and 'Campbell Early' Grapevines

“…All cold, drought, and salt stresses also stimulate the accumulation of compatible osmolytes and antioxidants (Hasegawa et al, 2000). Huang et al (2011) reported that accumulation of anthocyanin was enhanced by cold stress, and that transcript levels of CHI were dependent on interspecific backgrounds being elevated to much higher levels in Poncirus rootstock during cold acclimation. PAL and CHS mRNAs of Arabidopsis were accumulated coordinately in response to low temperatures in a light-dependent manner (Leyva et al, 1995).…”