Cellulase produced by rhizobia would soften the root hair cell wall enabling Rhizobium to penetrate and forming a trigger infection thread. In response the plant deposits a new layer of wall material at the infection site. Therefore, this study aimed to generate new recombinants of Rhizobium transconjugants that represent high cellulase activity to be used as bioinoculants in sustainable agriculture pathways. Cellulase activity was detected in 64 new recombinants isolated from eight conjugations compared with

the mid-parent of nine parental strains. From each conjugation, eight genotypes were isolated to be evaluated for cellulase activity. The variability in cellulase activity has a very wide range which may be related to the variations in the bacterial genotype. Among all transconjugants evaluated in this study, cellulase activities over the mid-parent ranged between 0.023-0.087. The highest activity (0.087) over the mid-parent was shown by new recombinants resulting from P3 × P7, followed by transconjugants

released from P2 × P6 (0.085) and transconjugants released from P4 × P6 (0.084). Meanwhile, the lowest activity over the mid-parent was shown by transconjugants derived from P4 × P7 (0.023). In the outlook, the superior genotypes in this guide may be functional to the elevated selection of novel cellulase activity, which allows transconjugants to better penetrate and form root nodules from the infection threads of their legume hosts.

Highlights

• Rhizobium can penetrate plant cells via producing cellulase and forming infection thread in this point.
• This study improved cellulase productivity from Rhizobium via inducing new recombinants to be select the superior genotypes.
• Generated transconjugants showed better expression in cellulase activity which allows to better penetrate and forming root nodules with their legume hosts from the infection threads.