การแสดงออกของยืนในกลุ่ม Phenylpropanoid ต่อความเข้ากันได้ของต้นตอยางพาราและกิ่งพันธุ์ดี

Abstract

Rubber tree is propagated by bud grafting. However, graft combinations may affect to growth and yield of the scion. The objective of this studied was to investigate the relations of graft combinations mechanism of rubber rootstocks and scions between homograft and heterograft. RRIM 600 and RRIT 251 were used as scion bud grafted onto PB 5/51 for heterograft (RRIM 600 / PB 5/51 and RRIT 251 / PB 5/51) or itself for homografts (RRIM 600 / RRIM 600 and RRIT 251 / RRIT 251). After bud grafting, gene expression, enzyme activity, secondary metabolite in the phenylpropanoid pathway and graft union formation were investigated. The result showed that homograft gave a higher survival rate and growth rate of scion than heterograft except for RRIM 600 bud grafted onto RRIM 600 rootstock. Initial graft union formation promoted filling of spaces by callus tissue until full spaces area at 10 days after bud grafting. RRIT 251 / RRIT 251 and RRIM 600 / PB 5/51 had callus tissue which develop better than RRIM 600 / RRIM 600 and RRIT 251 / PB 5/51.. This study can separate graft combination into 2 groups including compatible and less compatible combinations. Phenolic compounds rapidly increased at 5 days after bud grafting and became stable. For HOPAL gene expression in grafted plants rapidly increased at 3 days after bud grafting before declining and remained relatively unchanged during the latter stage. Accordance with PAL enzyme activity, which was highest increased at 3 days after bud grafting and subsequently decreased during 5-10 days after bud grafting. In addition, lignin accumulation was consistent with the level of HbCAD gene expression. Lignin content was highest increased at 10 days after bud grafting. HOCAD transcription level exhibited highest at 7 days after bud grafting. Higher phenolic compound content, HbPAL gene expression and PAL enzyme activity were found in less compatible group than compatible group. In contrast, lignin content and HbCAD gene expression was found higher in the compatible combinations than less compatible combinations. This study found that lignin content and HbCAD gene expression can be used as indicators for predict graft compatible ability between rubber rootstocks and scions.