Identification of a molecular marker associated with lignotuber in Eucalyptus ssp

Abstract

About 95% of Eucalyptus species present an organ known as a lignotuber, a basal woody swelling that holds a large number of dormant buds in a protected position along with carbohydrates and other nutrients. The importance of this trait in Eucalyptus species relates to its regenerative capacity, particularly in the context of coppicing practices and survival in regions of high abiotic stress, especially fire. In this study, we identified and characterized a genomic region associated with the lignotuber trait in commercially important Eucalyptus species by developing a polymorphic marker that co-segregates with lignotuber presence. The marker was then converted into a SCAR (Sequence Characterized Amplified Region) marker, validated in four other Eucalyptus species and hybrids and analyzed in silico. Our investigation presents a marker (ELig) that is effective in identifying individuals with lignotuber. In silico and Southern blot analyses show that the marker is present in a single copy region and is related to auxilin/cyclin-G associated kinase, containing a DnaJ domain. The ELig marker is an important tool that can be used to manage crosses in Eucalyptus breeding programs and inform studies involving lignotuber development and genetics. Eucalyptus is a widely planted tree genus due to its ability to adapt, grow, and produce quality wood that can be used for multiple end purposes 1,2. In Brazil, Eucalyptus plantations are extremely important as they comprise more than 71% of the total forest plantation area (5.56 million ha), making the country a leader in the forestry sector 3. In this context, researchers and foresters seek to implement tree improvement programs, advance silvicultural practices to increase productivity, introduce desirable traits, and reduce the environmental impacts of eucalypt plantations 4-6. A common practice in Eucalyptus management is coppicing, which offers an initial sprout growth rate greater than planting seedlings and is enhanced by the presence of an organ known as a lignotuber 7-9. Natural conditions in Australia led to the evolution of the Eucalyptus genus which is strongly associated with the occurrence of fire. Trees have been both survivors and promoters of fire over millions of years, leading to the development of a series of regeneration strategies including lignotubers 10. Lignotubers are basal, woody swellings that can form rapidly during the seedling stage 11-13. They hold a large number of dormant buds in a protected position, along with carbohydrates and nutrients necessary for bud development 11,12,14. Under normal conditions, the buds remain dormant, but they can be activated by stress factors, such as defoliation 14 , fire and coppicing 9,15 , and nutrient and water deficiencies 13,16 , underscoring the importance of the lignotuber for tree survival. These organs are present in 95% of all Eucalyptus species, including E. urophylla, E. brassiana, and E. saligna; however, some commercial species, such as E. grandis, E. regnans, E. delegatensis, E. pilularis, and E. niten...

Sapling and coppice biomass heritabilities and potential gains from Eucalyptus polybractea progeny trials

“…The reason for the divergent trends in heritability between sites is unclear and may be driven by the different environmental conditions at the three trials and contrasts with the findings from Osorio et al (2001) who found for E. grandis that heritabilities of tree volume and mean annual increments increased from 3 years old until 6 years old (harvest age). It was, however, expected that there would be divergence of performance in a mallee between the sapling and coppice assessments, on the basis of genetic control of lignotuber development in other eucalypt species (Bortoloto et al 2020;Walters et al 2005;Whittock et al 2003).…”

“…The higher differentiation between families postcoppicing at Drummartin seems to be an anomaly and was not repeated at the other two trials. This suggests that another factor is operating and may be explained, in part, by the genetic control of lignotuber development in some eucalypts species (Bortoloto et al 2020;Walters et al 2005;Whittock et al 2003). Walters et al (2005) demonstrated in a nursery experiment that E. obliqua with larger lignotubers had higher concentrations of carbohydrates and after decapitation, produced more above-ground biomass.…”

“…In order to maximise the potential of E. polybractea for cineole production, breeding focused on gains in foliar 1,8cineole concentration for the high-grade eucalyptus oil market (Boland et al 1991;Coppen 2002;Davis 2002). The market for eucalyptus oil with high levels of 1,8-cineole did not materialise and the potential for biomass for bioenergy (Abdullah and Wu 2009;McGrath et al 2016;Wu et al 2008) emerged as a greater potential avenue for profit (Bartle and Abadi Communicated by F.P.…”

“…Studies in other eucalypt species have revealed a wide range of genetic correlations between sapling and coppice biomass ranging from weak (Whittock et al 2003) to very strong (Amâncio et al 2020;Li et al 2012). This variation in genetic correlations may be underpinned by the genetic control of lignotuber development, which has been found to be responsible for the varying degrees of success of coppicing (Bortoloto et al 2020;Walters et al 2005;Whittock et al 2003).…”

Genome-Wide Analysis of Almond Skp1 Family Members And Identification of Self-Incompatibility-Related PsdSSK1

“…The PCR product obtained aft er labeling with digoxin was analyzed via 1% agarose gel electrophoresis and recov ered by an agarose gel purification recovery kit [64]. The cells were subsequently pr ehybridized at 37°C for 2 h, depleted of the prehybridization solution, added to the hybridization solution containing a digoxin-labeled probe, and hybridized overnight at 37°C [65]. After hybridization, the membrane was washed twice with 20 mL of 2× SSC and 0.1% SDS solution for 5 min each at room temperature.…”