过表达NtMYB4a基因通过调节激素平衡调控烟草植株生长发育

Over-expression of the NtMYB 4 a Gene Influences Tobacco Plant Growth Involved in Regulating Hormone Levels

MYB转录因子广泛参与植物的生长发育过程。前期研究发现NtMYB4a能影响烟株生长发育,但其调控机制未知。本研究通过分析过表达NtMYB4a(OE)植株与其野生型(WT)植株在旺长期根、茎、叶的表型及激素水平差异,探讨NtMYB4a对烟草生长发育的影响。结果表明:过表达NtMYB4a能显著提高烟草植株的株高、茎围、叶数和叶长,且OE植株茎尖中吲哚乙酸-谷氨酸(IAA-Glu)、2-甲硫基顺式玉米素核苷(2MeScZR)、水杨酸-2-O-β-葡萄糖苷(SAG)等激素水平显著高于WT,叶尖玉米素核苷(tZR)和脱落酸(ABA)含量显著高于WT,而赤霉素3(GA3)、SAG等含量则显著低于WT。相关性分析表明,株高与茎尖中ABA、L-色氨酸(TRP)、顺式玉米素(cZ)、12-氧-植物二烯酸(OPDA)、SAG、IAA-Glu、赤霉素20(GA20)呈显著正相关,与N-(3-吲哚乙酰基)-L-丙氨酸(IAA-Ala)、吲哚-3-甲酸(ICA)、赤霉素24(GA24)呈显著负相关。最大叶长与叶尖中tZR呈极显著正相关,与ABA呈显著正相关。茎围和叶数与激素含量无显著相关性。过表达NtMYB4a可能通过调节茎尖ABA、TRP、cZ、OPDA、SAG、IAA-Glu、GA20的含量促进茎的生长正向调控烟株株高,还可调节叶尖中tZR和ABA的含量促进叶片的伸长。

MYB transcription factors play a significant role in plant growth and development.Previous studies have suggested that NtMYB 4 a has an impact on tobacco plant growth,however,the precise mechanism of its effect has not yet been established.Our study aims to investigate how NtMYB 4 a affects tobacco growth and development by analysing phenotypic differences and hormone levels between overexpressed NtMYB 4 a(OE)plants and wild-type GDH88(WT)plants in roots,stems,and leaves at the peak of the growing season.The findings indicate that the overexpression of NtMYB 4 a substantially boosted tobacco plant growth,including the height,circumference,and number and length of leaves.Moreover,hormone levels of Indole-3-acetyl glutamic acid(IAA-Glu),2-Methylthio-cis-zeatin riboside(2MeScZR),and Salicylic acid 2-O-β-glucoside(SAG)in the tip of the stem of overexpressing plants were markedly higher than those in wild-type plants,while the concentrations of trans-Zeatin riboside(tZR)and Abscisic acid(ABA)in the leaf tip were also significantly higher than in wild-type plants.Conversely,concentrations of Gibberellin A3(GA3)and SAG were significantly lower in overexpressing plants compared to wild-type ones.Correlation analysis showed that plant height was significantly and positively correlated with ABA,L-tryptophan(TRP),cis-zeatin(cZ),cis(+)-12-Oxophytodienoic acid(OPDA),SAG,IAA-Glu,and Gibberellin A20(GA20)in the stem tip,and with N-(3-Indolylacetyl)-L-alanine(IAA-Ala),Indole-3-carboxylic acid(ICA),Gibberellin A24(GA24)were significantly negatively correlated.Maximum leaf length was highly significantly and positively correlated with tZR in leaf tip and significantly and positively correlated with ABA.Stem circumference and leaf number were not significantly correlated with hormone content.Overexpression of NtMYB 4 a may positively regulate tobacco plant height by regulating the content of ABA,TRP,cZ,OPDA,SAG,IAA-Glu,and GA20 in the stem tip to promote stem growth,and also regulating the content of tZR and ABA in the leaf tip to promote leaf elongation.